With increasing demand for liquid transportation fuels, decreasing reserves of ‘easy oil’ (crude petroleum oil that can be accessed and recovered easily) and increasing constraints on carbon footprints of such fuels, it is becoming increasingly important to develop routes to produce liquid transportation fuels from biomass in an efficient manner. Such liquid transportation fuels produced from biomass are sometimes also referred to as biofuels. Biomass offers a source of renewable carbon. Therefore, when using such biofuels, it may be possible to achieve more sustainable CO2 emissions over petroleum-derived fuels.
WO2010/053681 describes a biofuel production process comprising amongst others converting biomass to alcohol, and synthesizing a liquid hydrocarbon fuel from the alcohol. WO2010/053681 describes several processes for converting the biomass to alcohol. WO2010/053681 further mentions that alcohols may be directly oligomerized to hydrocarbons apparently in the absence of hydrogen at high temperatures (300-450° C.) and moderate pressures (1-40 atm.) in the presence of a zeolite catalyst in an oligomerization reactor (see also FIG. 10 of WO2010/053681). It is further indicated that by controlling the temperature and pressure of the oligomerization process and/or the composition of the zeolite, it is possible to direct the production of longer or shorter chain hydrocarbons. WO2010/053681 further mentions that it is also possible to control the amount of alkane branching in the final product. In its example 1, 27 tonnes of secondary alcohols are oligomerized at 350° C. at 10 atm. in the presence of zeolite catalyst and oxygen to produce 17 tonnes of gasoline and water. The alcohol to gasoline conversion apparently involves also a hydrogenation step. The approximate yield of gasoline based on weight of alcohol feed may be calculated to be approximately 63 wt %.
In its example 5, 27 tonnes of mixed ketones are converted to approximately 28 tonnes of secondary alcohols by hydrogenation over a nickel catalyst at approximately 130° C. and 15 atm hydrogen. The 28 tonnes of secondary alcohols are oligomerized at 350° C. at 10 atm. in the presence of zeolite catalyst to produce 12 tonnes of gasoline, 5 tonnes of light hydrocarbon residuals and 20 tonnes of water. The approximate yield of gasoline based on weight of alcohol feed may be calculated to be approximately 42 wt %.
In his thesis titled “TRANSFORMATION OF ACETONE AND ISOPROPANOL TO HYDROCARBONS USING HZSM-5 CATALYST”, obtainable from the Office of Graduate Studies of the Texas A&M University, USA, (December 2009), S. T. Vasquez describes a transformation of acetone and isopropanol to hydrocarbons using a HZSM-5 catalyst. The thesis describes that zeolite solid-acid catalyst HZSM-5 can transform either alcohols or ketones into hydrocarbons. Catalysts having a silica to alumina molar ratio (SAR) of 80 and 280 were used. Vasquez suggests for further studies to modify the catalyst HZSM-5 with metals such as Nickel or Copper.
In the processes of WO2010/053681 and Vasquez deactivation of the prior art catalysts may become an issue when the prior art processes would be applied on a commercial scale in a continuous manner. Without wishing to be bound by any kind of theory it is believed that operating the prior art processes for longer operating times may lead to excessive coking and subsequent deactivation of the catalysts.
For example Gayubo et al. in their article titled “Transformation of Oxygenate components of Biomass Pyrolysis Oil on a HZSM-5 Zeolite. I. Alcohols and Phenols”, published in Ind. Eng. Chem. Res. 2004, vol 43, page 2610 to 2618 and their article titled “Transformation of Oxygenate Components of Biomass Pyrolysis Oil on a HZSM-5 Zeolite. II. Aldehydes, Ketones, and Acids” published in Ind. Eng. Chem. Res. 2004, 43, 2619-2626 describe the effects of temperature and space time on the transformation over a HZSM-5 zeolite catalyst of several model components of the liquid product obtained by the flash pyrolysis of vegetable biomass (1-propanol, 2-propanol, 1-butanol, 2-butanol, phenol and 2-methoxyphenol). The HZSM-5 zeolite catalyst comprised 30 wt % bentonite, 45 wt % fused alumina and 25 wt % of a HZSM-5 zeolite having a Silica to Alumina molar ratio of 24. They explain that the viability of transforming oxygenates into hydrocarbons was found to be limited by the catalyst deactivation by coke, and that this deactivation effects the product distribution with time on stream. It would be an advancement in the art to provide a process for conversion of a feed containing one or more C3-C12 oxygenate(s), which process can be operated for a prolonged period of time without substantial deactivation of the catalyst.